This invention relates to surgical apparatus and methods in general, and more particularly to surgical apparatus and methods for the repair and/or replacement of the nucleus pulposus of an intervertebral disc.
The spinal column is a flexible chain of closely linked vertebral bodies. In a normal human spine, there are seven cervical, twelve thoracic and five lumbar vertebral bodies. Below the lumbar vertebrae are the sacrum and coccyx. Each individual vertebral body has an outer shell of hard, dense bone. Inside the vertebral body is a honeycomb of cancellous bone containing red bone marrow. All of the red blood cells, and many of the white blood cells, are generated inside such cancellous bone, where the blood cells mature before being released into the blood stream.
The intervertebral disc, which is also known as the spinal disc, serves as a cushion between the vertebral bodies so as to permit controlled motion. A healthy intervertebral disc consists of three components: a gelatinous inner core called the nucleus pulposus (or, more simply, the nucleus); a series of overlapping and laminated plies of tough fibrous rings called the annulus fibrosus (or, more simply, the annulus); and two (i.e., superior and inferior) thin cartilage layers, connecting the intervertebral disc to the thin cortical bone of the adjacent vertebral bodies, called the end plates.
An intervertebral disc may be displaced and/or damaged due to trauma (such as a herniated disc), or disease (such as a degenerative disc disease).
A herniated disc may bulge out and compress itself onto a nerve, resulting in lower leg pain, loss of muscle control or paralysis. To treat a herniated disc, the offending portions of the disc (i.e., the bulging portions of the nucleus) are generally removed surgically.
A degenerative disc disease typically causes the disc to gradually reduce in height, causing the annulus to buckle, tear or separate, radially and/or circumferentially, and causing persistent and disabling back pain. Degenerative disc disease is generally treated by surgically removing the nucleus and fusing together the adjacent vertebral bodies so as to stabilize the joint.
In either case, whether removing some or all of the nucleus, these procedures ultimately place greater stress on adjacent discs due to their need to compensate for the lack of motion. This may in turn cause premature degeneration of those adjacent discs.
Modern trends in surgery include the restoration, rather than the removal, of anatomical structures, with this restoration preferably being effected through the use of minimally invasive surgical techniques. The ability to surgically repair damaged tissues or joints, creating as few and as small incisions as possible, generally produces less trauma and pain for the patient while yielding better clinical outcomes.
In this respect it has been recognized that it may be possible to replace a damaged nucleus pulposus with a prosthetic implant, whereby to restore the spinal disc to its original configuration and function. Unfortunately, however, such implants, sometimes referred to as a xe2x80x9cprosthetic nucleusxe2x80x9d, tend to suffer from a variety of deficiencies.
A deficiency of current prosthetic nuclei is that they generally require relatively large or multiple incisions in the annulus in order to insert the prosthetic nucleus into the interior of the spinal disc. Such large or multiple incisions tend to further weaken an already compromised disc. Additionally, these incisions in the annulus are generally not easily repaired; thus, there can be a concern that the prosthetic nucleus may eventually work its way back out of the disc space and interfere with the surrounding anatomy.
A further deficiency of current, less-invasive prosthetic nuclei (see, for example, U.S. Pat. No. 5,674,295, issued Oct. 07, 1997 to Ray et al.) is that multiple, laterally-spaced implants typically have to be used to recreate the nucleus, which suggests that the side-by-side positioning of the several implants has to be carefully considered so as to ensure proper carrying of the load.
In pending prior U.S. patent application Ser. No. 09/559,899, filed Apr. 26, 2000 by Lehmann K. Li et al. for PROSTHETIC APPARATUS AND METHOD, which patent application is hereby incorporated herein by reference, and pending prior U.S. patent application Ser. No. 10/011,916, filed Nov. 05, 2001 by Lehmann K. Li et al. for APPARATUS AND METHOD FOR REPLACING THE NUCLEUS PULPOSUS OF AN INTERVERTEBRAL DISC OR FOR REPLACING AN ENTIRE INTERVERTEBRAL DISC, which patent application is hereby incorporated herein by reference, there are disclosed various prosthetic nuclei which, among other things, may be mechanically reshaped (e.g., by rolling, curling and/or folding) into a reduced footprint prior to deployment within the interior of the disc, whereupon it is restored to its original shape.
With this in mind, it would be advantageous to provide an apparatus and method for use in mechanically reshaping a prosthetic nucleus with a reduced footprint prior to deployment within the interior of the disc.
Accordingly, one object of the present invention is to provide improved apparatus for replacing the nucleus pulposus of an intervertebral disc.
Another object of the present invention is to provide an improved method for replacing the nucleus pulposus of an intervertebral disc.
And another object of the present invention is to provide improved apparatus for delivering a prosthetic nucleus into the inner portion of an intervertebral disc space.
Still another object of the present invention is to provide an improved method for delivering a prosthetic nucleus into the inner portion of an intervertebral disc space.
And still another object of the present invention is to provide improved apparatus for loading a prosthetic nucleus into a deployment cannula.
Yet still another object of the present invention is to provide an improved method for loading a prosthetic nucleus into a deployment cannula.
With the above and other objects in view, a feature of the present invention is the provision of a novel apparatus for implanting a prosthetic nucleus in a chamber of an intervertebral disc after removal of at least a portion of a damaged or degenerated nucleus from the chamber, the apparatus comprising:
a carrier cartridge defining a first end and a second end, the carrier cartridge having a cavity at the first end, the cavity being configured to selectively hold the prosthetic nucleus;
a deployment cannula having a proximal end and a distal end, the distal end of the deployment cannula being configured for implanting the prosthetic nucleus in the chamber of the intervertebral disc;
releasable connection means being located on at least one of the second end of the carrier cartridge and the distal end of the deployment cannula, the releasable connection means being configured to selectively connect the carrier cartridge and deployment cannula to one another;
a folding die being configured in at least one of the carrier cartridge and the deployment cannula, the folding die forming an inwardly decreasing taper in a direction from the cavity to the deployment cannula so as to reconfigure the prosthetic nucleus from a relatively flat configuration to a substantially cylindrical configuration as the prosthetic nucleus moves from the carrier cartridge to the deployment cannula; and
force applying means being configurable to impart a force on the prosthetic nucleus so as to cause the prosthetic nucleus to move from said cavity into said deployment cannula.
Another feature of the present invention is the provision of a novel apparatus for loading a prosthetic nucleus in a deployment cannula having a proximal end and a distal end, the distal end of the deployment cannula being configured for implanting the prosthetic nucleus in the chamber of the intervertebral disc, the apparatus comprising:
a carrier cartridge defining a first end and a second end, the carrier cartridge having a cavity at the first end, the cavity being configured to selectively hold the prosthetic nucleus;
releasable connection means being located on the second end of the carrier cartridge, the releasable connection means being configured to selectively connect the carrier cartridge and deployment to one another;
a folding die being configured in the carrier cartridge, the folding die forming an inwardly decreasing taper in a direction from the cavity to the deployment cannula so as to reconfigure the prosthetic nucleus from a relatively flat configuration to a substantially cylindrical configuration as the nucleus moves from the carrier cartridge to the deployment cannula; and
force applying means being configurable to impart a force on the prosthetic nucleus so as to cause the prosthetic nucleus to move from the cavity into the deployment cannula.
A further feature of the present invention is the provision of a novel method for implanting a prosthetic nucleus in a chamber of an intervertebral disc after removal of at least a portion of a damaged or degenerated nucleus from the chamber, the method comprising:
providing apparatus for implanting a prosthetic nucleus in a chamber of an intervertebral disc after removal of at least a portion of a damaged or degenerated nucleus from the chamber, the apparatus comprising:
a carrier cartridge defining a first end and a second end, the carrier cartridge having a cavity at the first end, the cavity being configured to selectively hold the prosthetic nucleus;
a deployment cannula having a proximal end and a distal end, the distal end of the deployment cannula being configured for implanting the prosthetic nucleus in the chamber of the intervertebral disc;
releasable connection means being located on at least one of the second end of the carrier cartridge and the distal end of the deployment cannula, the releasable connection means being configured to selectively connect the carrier cartridge and deployment cannula to one another;
a folding die being configured in at least one of the carrier cartridge and the deployment cannula, the folding die forming an inwardly decreasing taper in a direction from the cavity to the deployment cannula so as to reconfigure the prosthetic nucleus from a relatively flat configuration to a substantially cylindrical configuration as the prosthetic nucleus moves from the carrier cartridge to the deployment cannula; and
force applying means being configurable to impart a force on the prosthetic nucleus so as to cause the prosthetic nucleus to move from the cavity into the deployment cannula.
applying a force on the prosthetic nucleus in the direction of the cavity to the deployment cannula so as to cause the prosthetic nucleus to move through the folding die and become loaded into the deployment cannula;
placing the distal end of the cannula into the chamber of the intervertebral disc; and
ejecting the prosthetic nucleus from the deployment cannula so as to implant the prosthetic nucleus in the chamber of the intervertebral disc.
Another further feature of the present invention is the provision of a novel method for loading a prosthetic nucleus in a deployment cannula having a proximal end and a distal end, the distal end of the deployment cannula being configured for implanting the prosthetic nucleus in a chamber of an intervertebral disc, the method comprising:
providing apparatus for loading a prosthetic nucleus in a deployment cannula, the apparatus comprising:
a carrier cartridge defining a first end and a second end, the carrier cartridge having a cavity at the first end, the cavity being configured to selectively hold the prosthetic nucleus;
releasable connection means being located on the second end of the carrier cartridge, the releasable connection means being configured to selectively connect the carrier cartridge and deployment cannula to one another;
a folding die being configured in the carrier cartridge, the folding die forming an inwardly decreasing taper in a direction from the cavity to the deployment cannula so as to reconfigure the prosthetic nucleus from a relatively flat configuration to a substantially cylindrical configuration as the prosthetic nucleus moves from the carrier cartridge to the deployment cannula; and
force applying means being configurable to impart a force on the prosthetic nucleus so as to cause the prosthetic nucleus to move from the cavity into the deployment cannula; and
applying a force on the prosthetic nucleus in the direction of the cavity to the deployment cannula so as to cause the prosthetic nucleus to move through the folding die and become loaded into the deployment cannula.
And another further feature of the present invention is the provision of a novel prosthetic nucleus comprising:
a body adapted to be mechanically reshaped into a reduced footprint prior to deployment within the interior of a disc, whereupon it will be restored to its original shape; and
a plurality of filaments secured to the body, whereby the body may be drawn through a reshaping die and into a deployment cannula.